Calutron tank



llnite CALUTRON TANK James M. Cumming, Turtle Creek, Pa., and Leon R. Ludwig, Buiialo, N.Y., assignors, by mesne assignments, to the United States of America as represented by the United States Atomic Energy Commission Application July 24, 1946, Serial No. 685,928

3 Claims. (Cl. 250-419) This invention relates to calutrons and particularly to tanks that enclose the operating elements of such apparatus.

The term calutron designates apparatus by means of which separation of isotopes, or separation of material into components that respectively are enriched and impoven'shed in their contents of a given isotope, is accomplished on a practical scale, by the separating effect of a is especially adapted to enclose a highly evacuated chamber and to cooperate with a powerful electromagnet in such a way that a strong magnetic field is established through the chamber. The chamber contains the elements of the calutron system, comprising one or more ion sources each arranged to project a beam of accelerated .gaseous ions of the material to be separated in a direction normal to the lines of force of the field, so that the beam is curved in its passage, the respective components of the beam, due to their different mass to charge ratios following median paths having dififerent radii of curvature. A beam of charged particles that is curved in this way diverges as it leaves the ion source, such divergence occurring during a portion of its travel and being followed by convergence to a focus. Collection of a desired beam component is accomplished in a calutron by a suitable receiver properly positioned relative to the focal point of the component of the ion beam and so arranged as to separate and collect the desired component and to retain and de-ionize the charged particles making up such component.

A tank that is suitable for this type of service must have certain specialized characteristics. For convenience in operation and maintenance it is preferable that the system of operating elements be mounted on a common support so that the entire system can be removed as a unit. To permit this arrangement it is desirable that the operating chamber enclosed by the tank be entirely clear of obstructions, rendering it impractical to position structural elements for reinforcing the tank walls within the operating chamber. On the other hand the walls of the tank, especially those between the surfaces of which the magnetic field extends, must be rigid and capable of withstanding with negligible distortion or deflection, the forces imposed by both the magnetic field and external pressure caused by the high evacuation of the operating chamber. Any deflection of these walls would result in grates atent Patented Aug. 18, 1959 The main object of the invention is the provision of a tank having highly specialized construction rendering it suitable for use in a calutron.

\Another object is the provision in such a tank of a 5 novel wall structure capable of cooperating with a powerful electromagnet to set up within the tank a uniform or suitably modified magnetic field.

Another object is the provision in such a tank of a novel system for relatively positioning the sidewalls between which the magnetic field extends, and for' bracing all of the walls against distortion by either the magnetic field or external pressure, and which positioning and bracing system is arranged wholly outside the operating chamber enclosed by the tank Wall vStill another object is the provision of a novel joint arrangement between each of a pair of spaced side walls and an intermediate wall structure, providing an effective seal between the walls and cooperating with an external bracing system to accurately position the side walls, and also permitting the tank to be fabricated by a novel assembly procedure.

A final object is the provision of a novel procedure of fabricating a tank having characteristics rendering it suitable for calutron service.

In the accompanying drawings:

Fig. l is a Vertical sectional View of a tank constructed in accordance with the invention.

Fig. 2 is a sectional view on line 2-2 of Fig. 1, the elements of the operating system being omitted for clarity of the illustration of the tank assembly.

Fig. 3 is a detail sectional view on line 33 of Fig. 1.

Describing the drawings in detail, the tank therein illustrated, and constituting an embodiment of the invention, is adapted to be positioned in an air gap of a powerful electromagnet, so that the field of the latter extends through the tank. To this end, the tank comprises a pair of spaced heavy side walls 6 of magnetic material, having outer surfaces 7 that may be placed in contact with the poles of a magnet, thus making the walls 6 act as pole pieces setting up a magnetic field between them. Cooperating with the side walls 6 to enclose three sides of an operating chamber 8 is a U-shaped intermediate wall structure 9, which is preferably of non-magnetic material such as brass or stainless steel so as to have no distorting effect on the magnetic field.

The intermediate wall structure 9 is spaced inward from the edges 10 of the side walls 6, having flange-like marginal portions 11 of the latter extending outwardly from the intermediate Wall on the three sides of the operating chamber that such wall encloses. The ends 12 of the wall structure 9 are arranged closely adjacent the edges 13 of the side Walls 6, where they are welded to transverse elements 14 that have faces 15 arranged flush with the edges 13 and cooperating with such edges to define an open side 16 of the chamber 8.

Vacuum-tight connection between the intermediate wall structure 9 and the side walls 6 is made through U-shaped assemblies 17 of magnetic plates. These plates have surfaces 18 in face to face contact with the inner faces 19 of the side walls throughout areas extending about the three enclosed sides of the'operating chamber 8, and extending from inner margins 20 lying within and closely adjacent the boundaries of the operating chain-- her 8, between the edges 21 of the wall structure 9 and the adjacent inner faces of the respective side walls 6 and toward the edges 10 of the latter. The edges 21 of the wall structure 9 are connected to adjacent faces 22 of the plates 17 by continuous vacuum-tight welding, and the plates 17 are secured to the side walls 6 by similar welding.

The open sides of the U-shaped plate assemblies 17:

the U-shapcd intermediate wall 9, so that the inner faces 1? of the side walls 6 are uninterrupted from the edges 13 of lll'tB side walls 6 at the open side 16 of the chamber throughout the area lying inside theinner margins of the plate assemblies 1'7. The open side 16 of the chamber is adapted to be closed by a face plate, indicated diagrammatically at 23, suitable sealing being provided between such face plate and the surfaces of-the tank structure surrounding the open side 16 of the tank. Preferably the face plate is arranged to support the operating equipment that is positioned in the chamber 8, so that such equipment and face plate may be removed as a unit. At the side of the tank opposite the open side 16, the intermediate wall structure 9 is interrupted.

for coupling of a pumpout connection 24, the walls of which are secured to the adjacent tank structure by continuous vacuum-tight welding.

In apparatus of this kind it is essential that the inner faces 19 of the side walls 6 be plane and parallel in order to insure proper distribution of a magnetic field extending between them through the chamber 8. It is equally important that the side walls 6 be capable of resisting all distorting and deflecting influences, such as differences between external and internal pressure due to evacuation of the tank, and forces created by the magnetic field. It is also preferable that the intermediate wall be made of relatively light gauge material and reinforced against defiection. To provide the necessary rigidity and to accurately position the tank walls relative to each other, the following supporting and reinforcing system is provided.

Externally of the intermediate wall structure 9, and within the flange-like areas 1.1 of the side walls 6, plural bracing struts 25 are arranged in a series that extends about the three sides of the tank enclosed by the wall 9. Each of these struts 25 comprises a rectangular plate, preferably made of stainless steel or equivalent strong non-magnetic material, longitudinally extending transversely of the space between the side walls 6, and having ends 26 welded to the inner surfaces 22 of the plates 17. The inner edges 27 of the strut plates 25 are welded to the outer surfaces of the intermediate wall structure 9, from which the plates extend laterally toward the edges of the side walls. The elements 14, to which the ends of the wall structure 9 are welded, constitute members of the series of struts, being modified to provide contact surfaces '28 for scaling to a face plate and to form a suitable end structure for the wall 9. .Similar modified elements are arranged for coupling the pump-out connection 24 to the tank structure.

The open centers of the plates 17 provide spaces for mounting of shim plates 29 of magnetic material on the inner surfaces 19 of the side walls 6. Such plates may be used for the purpose of adjusting the distribution of the magnetic field to produce desired control of the path of the ion beam or beams that traverse it, and to adjust the focus of such beam or beams. The plates 29 may be bolted to the side walls 6, in contact with the inner faces 19 of such Walls, the surfaces 30 of the plates 2? that are exposed within the chamber 8 being contoured to produce the required distribution of the magnetic field.

Fig. 1 illustrates diagrammatically the essential elements af a calutron system. This system comprises a liner 31 within which ion beams 32 travel along arcuatte paths from sources 33, suitably supported on the face plate 23, and comprising apparatus for vaporizing and ionizing the material to be treated, and projecting accelerated. beams of the ions. Under the influence of" the magnetic field, which extends normally to the difC-. tion of beam travel, the beams 32 curve through 180", diverging through the first '90 andthereafter converging to foci at 34. Receivers'35 are located adjacent the .two

foci 34 for respectively separating the components of the beams that contain concentrations of the desired constituent. V

plates.

In fabricating a tank arranged as described above, the following methods may be employed, resulting in accurate positioning of the side walls 6 relative to each other to give to their inner surfaces 19 the requisite plane and parallel disposition. A subassembly, or supporting frame is "welded upfcomprising the intermediate wall structure 9, the struts 25, and the U-shaped assemblies 17 of The heat developed by welding together the edges of the intermediate wall 9 and the plates of the assemblies 17 continuously throughout their extent is apt to distort the plates of the assemblies 17. To correct distortion of the side wall-contacting surfaces 18 of these plates, such surfaces are machined to plane and parallel condition following the operation of welding up the subassembly. After the machining has been accomplished, the side walls 6 are added to the assembly, their faces 19, which are previously machined to plane condition, being brought into contact with the machined, parallel surfaces 18 of the plate assemblies 17. The faces 19 of the side walls 6 are thereby brought accurately to the required parallel positions. Welding of the side walls 6 to the plate assemblies 17 is readily accomplished since the plates and side walls are both made of magnetic material, and preferably of identical material, and are of very heavy gauge, being for example, of the order of 1% and 3% inch thickness respectively.

A tank constructed as described above is peculiarly suitable for calutron service. The assembly of side walls, and intermediate wall and plates in face to face contact with the side walls provides a type of joint that is readily welded into a vacuum-tight connection, requiring a minimum amount of welding, particularly in the final assembly operation of securing the side walls to the subassembly. The arrangement of the tank elements, coupled with the described method of fabrication provides accurate relative positioning of the inner faces 19 of the 7 side walls, and the requisite plane condition of such faces.

The embodiment of the invention-herein disclosed is representative of a preferred form. The disclosure is to be interpreted in an illustrative rather than a limiting sense, the scope of the invention being determined in accordance with the claims appended hereto.

We claim:

1. An open-sided calutron tank comprising a pair of heavy magnetically permeable side walls, a non-magnetic U-shaped intermediate wall structure spaced inward from the edges of the side Walls and arranged between and cooperating With the side Walls to enclose three sides of an operating chamber, a pair of U-shaped magnetically permeable plate'assemblies respectively arranged in face to face contact with areas of the side walls outside the intermediate wall structure, said plates extending between the intermediate wall structure and the respective ad-' jacent sidewalls and-having their open sides coinciding with theopen side of the intermediate wall structure, and plural non-magnetic struts arranged in a series around the outside of the intermediate wall structureand extending betweenthe U-shaped plate assemblies.

2. A calutron tank assembly comprising a pair of heavy magnetically permeable side walls, an intermediate wall structure between the side walls arranged to cooperate'with themto enclose an operating chamber, an open-centered plate structure disposed in face to'face contact with inner faces of the side walls, saidplate structures having inner margins Within the. chamber, bracing struts extending between the said plate structures,

and magnetically permeable shim plates secured to the side wallsand lyin'g within' the open centers of the plate structures. j I I l V.

3. A calutrontankassembly comprising a pair of heavy magnetically permeable, side walls, a U-shaped in- 1 termediate-wall structure between the side walls and cooperating with themto enclose an open-sided operating hamber, a pair of U-shaped magnetically permeable 6 plate assemblies respectively disposed between the inter- References Cited in the file of this patent mediatewall structure and ad acent side walls, said plate UNITED STATES PATENTS assembhes being m face to face contact with mner faces of the side walls and having their open sides coinciding 1,429,927 Cartel: P 26, 1922 with the open side of the operating chamber, and mag- 5 2,373,270 Skolmk P 1945 netically permeable shim plates arranged within the openings of the plate assemblies and secured in face to face FOREIGN PATENTS contact with the side wall. 108,592 Austria Mar. 18, 1926 

